---
description: Testing patterns with Vitest
globs: ["apps/sim/**/*.test.ts", "apps/sim/**/*.test.tsx"]
---

# Testing Patterns

Use Vitest. Test files live next to source: `feature.ts` → `feature.test.ts`

## Structure

```typescript
/**
 * Tests for [feature name]
 *
 * @vitest-environment node
 */

// 1. Mocks BEFORE imports
vi.mock('@sim/db', () => ({ db: { select: vi.fn() } }))
vi.mock('@sim/logger', () => loggerMock)

// 2. Imports AFTER mocks
import { describe, expect, it, vi, beforeEach, afterEach } from 'vitest'
import { createSession, loggerMock } from '@sim/testing'
import { myFunction } from '@/lib/feature'

describe('myFunction', () => {
  beforeEach(() => vi.clearAllMocks())

  it('should do something', () => {
    expect(myFunction()).toBe(expected)
  })

  it.concurrent('runs in parallel', () => { ... })
})
```

## @sim/testing Package

```typescript
// Factories - create test data
import { createBlock, createWorkflow, createSession } from '@sim/testing'

// Mocks - pre-configured mocks
import { loggerMock, databaseMock, fetchMock } from '@sim/testing'

// Builders - fluent API for complex objects
import { ExecutionBuilder, WorkflowBuilder } from '@sim/testing'
```

## Rules

1. `@vitest-environment node` directive at file top
2. **Mocks before imports** - `vi.mock()` calls must come first
3. Use `@sim/testing` factories over manual test data
4. `it.concurrent` for independent tests (faster)
5. `beforeEach(() => vi.clearAllMocks())` to reset state
6. Group related tests with nested `describe` blocks
7. Test file naming: `*.test.ts` (not `*.spec.ts`)